This bolt of Mr. MonotaRO has been used for several years, but this part of M6 × 20 is broken only in a place where load is applied. Until now, there was not something once every five years, in some cases it broke in one year. I can not think that the allowable load is just barely visible. Because this part mounting has not changed for more than 20 years. Looking at the broken part, it does not look like it contains "s". I do not know whether it is made in Japan or in China, but there is no doubt that there is something different. For that reason, I am considering changing that part to stem bolt. Although it is cheap, there are merits to change in a small amount, we are doing a different test from the laboratory, so I guess from this result that there is a problem with the yield. I need attention.